Blends containing proteases

ABSTRACT

Described are compositions, in particular lyophilizates, containing proteolytic enzymes, and methods for producing the compositions. Typically these compositions contain one or more proteases with collagenase activity and a neutral protease, for example, thermolysin. The compositions are free of acetate salts. Surprisingly, such compositions can be dissolved in water more rapidly than lyophilized protease mixtures of the state of the art.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/699,299 filed Apr. 29, 2015, now abandoned, which is a continuationof U.S. application Ser. No. 13/230,927 filed Sep. 13, 2011, abandoned,which is a continuation of PCT/EP2010/001687 filed Mar. 17, 2010 andclaims priority to European applications EP 09005257.2 filed Apr. 9,2009 and EP 09003967.8 filed Mar. 19, 2009, the disclosures of which arehereby incorporated by reference in their entirety.

FIELD

The present invention provides compositions, preferably lyophilizates,comprising proteolytic enzymes. Preferred compositions comprise one ormore proteases with collagenase activity and a neutral protease,preferably thermolysin. According to the invention, the compositions arefree of acetate salts. Surprisingly, such compositions can be dissolvedin water more rapidly than lyophilized protease mixtures of the state ofthe art.

BACKGROUND

The process of disintegrating a mass of interconnected cells (tissue)wherein the cells are separated from each other is known as “tissuedissociation”. Tissue dissociation is a principal application forcertain proteolytic enzymes in tissue culture research and cell biologystudies. Blends of proteolytic enzymes, rather than single proteases,are used for the dissociation of biological tissue.

The biological tissue is preferably obtained (i.e., explanted) from ananimal, preferably from a mammal, and more preferred from a human. Thebiological tissue is incubated in an aqueous medium containing theproteolytic enzymes in active form. By way of hydrolyzing peptidic bondsin the extracellular matrix, the interconnected cells become separablefrom each other.

Despite the widespread use of enzymes for these applications over theyears, many parameters influencing the tissue dissociation process andthe harvesting of dissociated target cells are not well understood. As aresult, the skilled person's choice of one particular protease or blendof proteases, or one certain technique over another has often beenarbitrary and based more on past experience than on an understanding ofwhy the protease-mediated process works and what modifications couldlead to even better results.

Due to the fact that collagen has a major structural role in thepreferred tissues, proteolytic enzymes with collagenase activity areused with advantage in many processes of tissue dissociation known tothe art. Blends containing a plurality of proteases usually comprisecollagenases.

Collagenases (EC 3.4.24.3) are metalloproteinases, proteolytic enzymeswhich are able to hydrolyze collagen, both in its native triple-helixand denatured conformation, by dissociating its peptidic bonds underphysiological conditions of pH and temperature. Several collagenasesproduced by bacteria are well known in the state of the art.Collagenases produced by bacteria of the Clostridium species, inparticular Clostridium hystolyticum are of major interest forapplications in tissue dissociation.

In aqueous solution, the collagenases and particularly collagenase I arestable only to a limited extent, even at low temperatures. Particularcare is in fact necessary when preparing and handling collagenasesolutions, in order to prevent inactivation of enzymatic activity: atemperature above 56° C. is detrimental, as well as the presence ofseveral metal ions and of chelating agents interacting with the Ca2+ions that are essential in the collagenase structure. The optimal pHvalue for the storage of collagenases ranges from about 6 to about 8 forcrude preparations, while the interval is much narrower when thecollagenase isoforms are purified; low pH values can inactivateenzymatic activity. Besides, collagenases are sensitive to physicaltreatment such as freezing, thawing, lyophilization and drying. Thesetreatments, which are often necessary for the purification andpreparation of dry products, pose a technical problem in that they mayreduce the desired enzymatic activity or may even provoke inactivationof the collagenase enzymes. Collagenase I and/or II isoforms in theirlyophilized powder form maintain reasonable stability if kept attemperatures which are lower than 25° C., preferably between about 2° C.and 8° C., in sealed bottles and avoiding exposure to humidity. However,the low stability of collagenase isoforms in the presence of water andparticularly in the added presence of a further protease such asthermolysin or dispase determines several problems in the preparation ofblends, lyophilizates, and compositions for use in tissue dissociation.

Thermolysin [EC 3.4.24.27; CAS registry number 9073-78-3] is athermostable neutral metalloproteinase (also referred to herein as“neutral protease”) produced in the culture broth of Bacillusthermoproteolyticus (Endo, S., J., Ferment. Technol. 40 (1962) 346-353;Matsubara, H., Feder, J., in: 3rd ed., Boyer, P., D., (Ed.), TheEnzymes, Vol. 3, Academic Press, New York, 1971, pp. 721-795). Itrequires one zinc ion for enzyme activity and four calcium ions forstructural stability (Latt, S., A., et al., Biochem. Biophys. Res.Commun. 37 (1969) 333-339; Feder, J., et al., Biochemistry 10 (1971)4552-4556; Tajima, M., et al., Eur. J. Biochem. 64 (1976) 243-247) andcatalyzes specifically the hydrolysis of peptide bonds containinghydrophobic amino acid residues (Morihara, K., and Tsuzuki, H., Eur. J.Biochem. 15 (1970) 374-380; Inouye, K., et al., Biochem. J. 315 (1996)133-138).

Roche Applied Science has developed LIBERASE enzymes (commerciallyavailable from Roche Diagnostics GmbH, Mannheim, Germany) which areblends of highly purified enzymes, designed to improve the quality andreproducibility of tissue dissociation, and improve the health ofisolated cells. LIBERASE enzyme technology comprises the methods forpurifying Clostridial collagenase isoforms to high specific activity,and for blending them together with high specific activity neutralprotease in optimal ratios for effective dissociation of primarytissues. In the manufacturing process highly purified collagenase I andcollagenase II are collected. These two collagenase isoforms are blendedin a predetermined ratio with each other, and with a non-Clostridialneutral protease. The type of neutral protease is specifically chosen,and differs according to the final product. For example, LIBERASEBlendzyme 1 contains the neutral protease dispase, and LIBERASEBlendzyme 2 contains the neutral protease thermolysin.

LIBERASE enzymes are available for customers as lyophilizates; the sameapplies to a number of products from other manufacturers (e.g.,Worthington Biochemical Corporation, Lakewood, N.J., USA) for the sameintended use. The lyophilizates known to the art comprise one or morecollagenase enzyme and/or one or more further protease, such as (but notlimited to) thermolysin and dispase. In addition, the lyophilizatescomprise certain helper substances which are present in the enzymepreparation or enzyme mixture, and which stabilize one or more enzymesin solution and/or during lyophilization. In addition, certainproteolytic enzymes can be crystallized in the presence of a helpersubstance. The solid material obtained upon crystallization cantherefore also contain the helper substance.

Freeze-drying, also referred to as lyophilization or cryodesiccation, isa dehydration process typically used to preserve a perishable materialor make the material more convenient for storage and/or transport.Freeze-drying works by freezing the material and then reducing thesurrounding pressure and adding enough heat to allow the frozen water inthe material to sublime directly from the solid phase to gas.

Before use, any lyophilisate comprising one or more proteases has to bedissolved. The inventors have surprisingly found that one candramatically reduce the time needed to dissolve a lyophilisatecomprising a blend of collagenase enzymes and a neutral protease. Thekey to an enhanced solubility appears to be certain ionic compounds. Inthe presence of these compounds lyophilized protease material gains animproved contact with the aqueous solvent which aids dissolving theproteases. The time between contacting the lyophilisate with the aqueoussolvent and complete solubilization of the lyophilizate is a crucialparameter limiting the quality of the proteolytic agents. The shorterthis period, the less the proteolytic enzymes degrade each other, themore proteolytic activity is applied to the target tissue to bedissociated. Apart from shortening the absolute time span needed forsolubilizing the lyophilizate, the variation of said time span could beminimized, too. This is particularly advantageous in terms ofreproducibility of the enzymatic activity applicable in the subsequenttissue dissociation workflow. The smaller the variation, the higher thereproducibility.

SUMMARY

A first embodiment of the invention is a solid composition obtainable bythe steps of (a) preparing a homogeneous solution of an acetate-freepreparation of a neutral protease in an aqueous acetate-free low-saltsolution; (b) adding a neutral salt to the homogeneous solution of step(a) and dissolving the neutral salt, thereby making a stabilizedsolution wherein said stabilized solution additionally comprises abuffer salt buffering in the range of about pH 6 to about pH 8.5, andwherein the stabilized solution further comprises calcium chloride; (c)mixing the stabilized solution of step (b) with an acetate-freepreparation of one or more proteolytic enzymes with collagenaseactivity, and making a homogeneous solution; (d) freeze-drying thesolution of step (c), thereby obtaining the solid composition of theinvention.

A further embodiment of the invention is a solid composition obtainableby the steps of (a) dissolving an acetate-free preparation of a neutralprotease, preferably thermolysin from Bacillus thermoproteolyticus, inan aqueous acetate-free low-salt solution, wherein the solutioncomprises a buffer salt capable of buffering in the range of about pH 6to about pH 8.5 and further comprises calcium chloride, and making ahomogeneous solution; (b) adding a neutral salt to the homogeneoussolution of step (a) and dissolving the neutral salt, thereby making astabilized solution; (c) mixing the stabilized solution of step (b) withan acetate-free preparation of one or more proteolytic enzymes withcollagenase activity, and making a homogeneous solution; (d)freeze-drying the solution of step (c); thereby obtaining the solidcomposition of the invention.

A further embodiment of the invention is a method to produce acomposition according to the invention, the method comprising the stepsof (a) dissolving an acetate-free preparation of a neutral protease,preferably thermolysin from Bacillus thermoproteolyticus, in an aqueousacetate-free low-salt solution, wherein the solution comprises a buffersalt capable of buffering in the range of about pH 6 to about pH 8.5 andfurther comprises calcium chloride, and making a homogeneous solution;(b) adding a neutral salt to the homogeneous solution of step (a) anddissolving the neutral salt, thereby making a stabilized solution; (c)mixing the stabilized solution of step (b) with an acetate-freepreparation of one or more proteolytic enzymes with collagenaseactivity, and making a homogeneous solution; (d) freeze-drying thesolution of step (c); thereby producing the solid composition of theinvention.

Another embodiment of the invention is a solid composition comprisingone or more proteolytic enzymes with collagenase activity and a neutralprotease characterized in that the composition is free of acetate salt.

Yet, a further embodiment of the invention is a method to prepare asolution with proteases, comprising the step of contacting a compositionaccording to the invention with water.

Yet, a further embodiment of the invention is an aqueous solutioncomprising water and a composition according to the invention.

Yet, a further embodiment of the invention is the use of an aqueoussolution according to the invention for treating a biological tissue.

Yet, a further embodiment of the invention is a kit comprising one ormore containers containing a composition according to the invention.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A shows a photograph of a lyophilizate with unordered clusters ofcrystals.

FIG. 1B is a lyophilizate with crystals having a lamellae- or blade-likestructure.

DETAILED DESCRIPTION

It was a surprising finding by the inventors that the surface area of alyophilizate was greatly increased when the lyophilizate was preparedfree of acetate salts. Typically, the lyophilizate according to theinvention has a lamellar structure with an increased surface, comparedto the lyophilizates known to the state of the art. Thus, thelyophilizates according to the invention have enhanced characteristicsas to the time needed to dissolve them. This property is of greatadvantage because the time during which the proteases in solutiondegrade each other is significantly reduced.

In addition, the lyophilizates according to the invention are dissolvedto form clear, homogeneous solutions. That is to say, no precipitateoccurs. Thereby protease solutions of high, reproducible quality areprovided.

Certain technical terms are used with particular meaning, or are definedfor the first time, in this description of the present invention. Forthe purposes of the present invention, the terms used are defined bytheir art-accepted definitions, when such exist, except that when thosedefinitions conflict or partially conflict with the definitions setforth below. In the event of a conflict in definition, the meaning of aterm is first defined by any of the definitions set forth below.

The term “comprising” is used in the description of the invention and inthe claims to mean “including, but not necessarily limited to”.

The articles “a” and “an” are used herein to refer to one or to morethan one (i.e., to at least one) of the grammatical object of thearticle. By way of example, “a compound” means one compound or more thanone compound.

When designating a range of numerical values such as a concentrationrange, the range is indicated by the word “between”, followed by a firstvalue n1 and a second value n2. The lower boundary of the designatedrange is understood as being the value equal to or higher than the firstvalue. The higher boundary of the designated range is understood asbeing the value which is equal to or lower than the second value. Thus,a value x in the designated range is given by n1≦x≦n2.

If not stated otherwise, it is understood that the term “about” and thecharacter “˜” in combination with a numerical value n (“about n”, “˜n”)indicates a value x in the interval given by the numerical value±5% ofthe value, i.e., n−0.05*n≦x≦n+0.05*n. In case the term “about” or thecharacter “˜” in combination with a numerical value n describes apreferred embodiment of the invention, the value of n is most preferred,if not indicated otherwise.

A “mixture” is a substance made by combining two or more differentmaterials with no chemical reaction occurring. The objects do not bondtogether in a mixture. A mixture can usually be separated back into itsoriginal components. Mixtures are the product of a mechanical blendingor mixing of chemical substances like elements and compounds, withoutchemical bonding or other chemical change, so that each ingredientsubstance retains its own chemical properties and makeup. While thereare no chemical changes in a mixture, physical properties of a mixture,such as its melting point, may differ from those of its components.

A lyophilizate is an example for a mixture which is a solid. In thecontext of the present invention such a mixture comprises one or moreproteinaceous compounds. Preferably, these are one or more proteolyticenzymes with collagenase activity and a neutral protease. Preferably,the neutral protease is thermolysin. Also preferred, a lyophilizateadditionally comprises a buffer salt, and further helper compounds whichstabilize the proteinaceous compounds. The helper compounds can be ionicor non-ionic. Examples for ionic compounds are an organic salt and aninorganic salt. Examples for non-ionic compounds are an organic polymer(such as, but not limited to polyethylene glycol, and starch) and apolyol (such as, but not limited to a sugar and a sugar alcohol).Further helper compounds are possible.

Mixtures are either heterogeneous or homogeneous. Homogeneous mixturesare mixtures that have definite, consistent properties. Particles areuniformly spread. For example, any amount of a given mixture has thesame composition and properties. A homogeneous mixture is a uniformmixture consisting of only one phase.

A solution is a homogeneous mixture of one or more substances (thesolutes) dissolved (i.e., dissociated) in another substance (thesolvent). A common example would be a solid dissolving into a liquid(i.e., salt or protein dissolving in water). Solubility is a compoundproperty. Depending on the composition of the mixture to be dissolvedand conditions (e.g., temperature, type of solvent, solutes present inthe solvent), the amount of a substance that can dissolve in a solutioncan be variable.

Examples for non-homogeneous (heterogeneous) mixtures are a colloid anda suspension. In the context of the invention, a suspension isunderstood as being a heterogeneous fluid containing solid particlesthat are sufficiently large for sedimentation. Unlike colloids, thesuspended particles settle over time if left undisturbed. Thisdistinguishes a suspension from a colloid in which the suspendedparticles are smaller and do not settle.

In a solution, the dissolved substance does not exist as a solid, andsolute(s) and solvent are homogeneously mixed. The term “stability” of asolution refers to the tendency of the dissolved substance to remain inthe dissolved state. That is to say, the term refers to the ability ofthe solution to remain homogeneous during a given time interval.Stability can therefore be characterized in a quantifying way bydetermining said time interval. Thus, the dissolved substance in a firstsolution characterized by a lower stability exhibits a higher tendencyto precipitate or form a colloid, as opposed to a second solutioncharacterized by a higher stability in which said tendency is lower. Asa consequence, after a certain amount of time said first solutionbecomes a heterogeneous mixture whereas said second solution remains ahomogeneous mixture.

Turbidity is a measure of water cloudiness caused by the presence ofparticles in a suspension or a colloid. There are several practical waysof determining turbidity, the most direct being some measure ofattenuation (that is, reduction in strength) of light as it passesthrough a sample column of water. Thus, one way to determine turbidityis visual inspection, i.e., inspection by eye.

Another way of determination is measurement of light attenuation with aphotometer. In this regard, the term “Optical density” (also referred toas “OD”) denotes a unit-less measure of the transmittance of an opticalelement for a given length at a given wavelength λ:

OD _(λ)=log₁₀ O=−log₁₀ T=−log₁₀(I/I ₀)

wherein

-   -   O=the per-unit opacity    -   T=the per-unit transmittance    -   I₀=the intensity of the incident light beam    -   I=the intensity of the transmitted light beam.

The higher the optical density, the lower the transmittance. Owing tothe scattering of a light beam focused on the particles the opticaldensity of a suspension or a colloid is increased compared to a clearsolution.

The composition of a lyophilizate has a consequence for the amount ofthe solid matter which can be dissolved in a given solvent. However, thecomposition of a lyophilizate also significantly impacts on the timeneeded for dissolving the solid matter in the solvent. A central objectof the invention was to provide compositions and conditions whichaccelerate the formation of aqueous solutions of lyophilizatescontaining a certain amount of proteinaceous constituents. To this end,some further theoretical background is presented aiding theunderstanding of the invention.

The term “sink conditions” describes a dissolution system that issufficiently dilute so that the dissolution process is not impeded byapproach to saturation of the compound of interest. In the presentcontext, the compound of interest can be each constituent of aparticular lyophilizate or the lyophilizate itself.

An important physical measurement required is that of solubility of acompound of interest at a given temperature. Once the solubility isknown, the volume of solvent or the acceptability of a particularsolvent can be determined. For example, sink conditions are consideredto exist if, at the dissolution of 100% of the highest strength of thelyophilizate to be tested, a concentration of preferably not more thanabout ⅔, more preferred not more than about ½, even more preferred notmore than about ⅓ of saturation is achieved.

The dissolution of a solid in a bulk liquid is a dynamic process, sincemolecules migrate from the solid particle into the diffusion layer thatsurrounds the particle. Then, these molecules diffuse from the diffusionlayer into the bulk solution. Provided that during the dissolution ofthe particles so-called sink conditions are met, the dissolutionkinetics are described by Equation (1).

C(t)=c _(s)×(1−e ^(−k×t))  (1)

With the so-called Noyes-Whitney equation (Noyes, A. A. & Whitney, W.R., J., Am. Chem. Soc. 19 (1897) 930-934), the concentration of themolecule in the bulk solution (c(t)) can be calculated from theconcentration of the molecule in the diffusion layer or the so-calledsolubility of the drug (c_(s)), the time (t) and the rate constant ofdissolution (k). The latter can be calculated by Equation (2) from thesurface of the particles (S), the diffusion coefficient of the dissolvedmolecule (ξ) the volume of the bulk solution (V_(s)) and the thicknessof the diffusion layer (h).

$\begin{matrix}{k = \frac{S \times \xi}{{Vs} \times h}} & (2)\end{matrix}$

According to the Stokes Equation (3), the diffusion coefficient (ξ) canbe calculated from the Boltzmann constant (k_(b)), the temperature (T),the viscosity of the bulk solution (η) and the hydrodynamic radius ofthe dissolved molecule (r).

$\begin{matrix}{\xi = \frac{k_{b} \times T}{6\pi \times \eta \times r}} & (3)\end{matrix}$

The surface area (S) of a given volume of a solid lyophilizate isdetermined by the surface area of the particles. Substitution inEquation (2) shows that for ideal particles the rate constant ofdissolution (k) is inversely proportional to the diameter of theparticles.

For several particle sizes one finds that small particles will dissolvemuch quicker than bigger particles as with smaller particles a largersurface area gets into contact with the solvent. In case the sizedistribution of the particles gets broader, the average rate constant ofdissolution will become less accurate, thus leading to a less accurateprediction of the dissolution profile. That is to say, the dissolutionbehavior of a lyophilizate is the result of the cumulative effect of allparticles in the solid matter.

A first embodiment of the invention is a solid composition obtainable bythe steps of (a) preparing a homogeneous solution of an acetate-freepreparation of a neutral protease in an aqueous acetate-free low-saltsolution; (b) adding a neutral salt to the homogeneous solution of step(a) and dissolving the neutral salt, thereby making a stabilizedsolution wherein said stabilized solution additionally comprises abuffer salt buffering in the range of about pH 6 to about pH 8.5, andwherein the stabilized solution further comprises calcium chloride; (c)mixing the stabilized solution of step (b) with an acetate-freepreparation of one or more proteolytic enzymes with collagenaseactivity, and making a homogeneous solution; (d) freeze-drying thesolution of step (c), thereby obtaining the solid composition of theinvention.

The compositions according to the invention are lyophilizates, that isto say products of a freeze-drying process. Said compositions typicallyhave a residual moisture content which is in the range of about 0.01%[w/w] to about 5% [w/w], preferred in the range of 0.1% to 3% [w/w],even more preferred in the range of 1% to 2% [w/w]. Generally, theskilled person aims at minimizing the moisture content since this factoradvantageously influences product shelf life.

According to the invention, the lyophilized composition comprising oneor more proteolytic enzymes with collagenase activity and one or moreneutral proteases is characterized by an enhanced solubility in anaqueous solvent, preferably water, if the composition is free of acetatesalt. Examples of an acetate salt are sodium acetate, potassium acetateand calcium acetate.

In Example 2 below a first crystallization process for thermolysin isdisclosed. The thermolysin crystals according to this state-of-the-artprocess form in the presence of calcium acetate, and this acetate saltis comprised in the crystals. In a blending process the acetate crystalscan be dissolved but the solution of the neutral protease is instable inthat thermolysin tends to precipitate.

The present invention is based on the first finding that the stabilityof a homogeneous solution of thermolysin is enhanced by the absence ofacetate ions. For this reason, an acetate-free preparation ofthermolysin has to be provided and used, in order to practice thepresent invention. To this end, the THERMOASE preparation of thermolysincan be used.

A further important finding of the inventors was that a stable solutionof thermolysin is obtained when (i) THERMOASE is dissolved in a low-saltbuffer to yield a homogeneous solution, and (ii) a neutral salt,preferably sodium chloride, is dissolved subsequently in saidhomogeneous solution of (i).

In view of the inventor's basic findings, an embodiment of the inventionis a solid composition obtainable by the steps of (a) dissolving anacetate-free preparation of a neutral protease, preferably thermolysinfrom Bacillus thermoproteolyticus, in an aqueous acetate-free low-saltsolution, wherein the solution comprises a buffer salt capable ofbuffering in the range of about pH 6 to about pH 8.5 and furthercomprises calcium chloride, and making a homogeneous solution; (b)adding a neutral salt to the homogeneous solution of step (a) anddissolving the neutral salt, thereby making a stabilized solution; (c)mixing the stabilized solution of step (b) with an acetate-freepreparation of one or more proteolytic enzymes with collagenaseactivity, and making a homogeneous solution; (d) freeze-drying thesolution of step (c); thereby obtaining the solid composition of theinvention.

The low-salt solution of step (a) preferably comprises (and morepreferred consists of) water, CaCl₂ and an organic buffer salt. Thepreferred buffer salt is HEPES but other buffer salts are possible. Theaggregate concentration of dissolved salts in the low-salt solution ofstep (a) is preferably in the range of about 1 mM to about 250 mM, morepreferred in the range of about 5 mM to about 100 mM, even morepreferred in the range of about 10 mM to about 50 mM, and most preferredabout 25 mM.

The neutral salt in step (b) is preferably sodium chloride. In a verymuch preferred embodiment of the invention, prior to step (c) thesolution of the neutral protease is subjected to an adjustment ofdissolved ions and/or a removal of low molecular weight proteinfragments. This can be done, for example, by way of diafiltration. Avery much preferred stabilized solution obtained in step (b) preferablycomprises thermolysin at a concentration in the range of about 0.5 mg/mlto about 5 mg/ml, more preferred in the range of about 1 mg/ml to about3 mg/ml. The non-proteinaceous compounds in the solution preferablycomprise CaCl₂, a neutral salt, and an organic buffer salt capable ofbuffering in the range of about pH 6 to about pH 8.5. The conductivityof the stabilized solution obtained in step (b) is preferably in therange of about 20 mS/cm to about 23 mS/cm.

A main advantage of the stabilized solution is that the neutralprotease, particularly thermolysin, remains stable in homogeneoussolution for a longer time, compared to the situation before whenstate-of-the-art methods involving acetate-containing preparations wereused. In blending processes aiming at the formulation of mixtures ofseveral proteases including thermolysin, enhanced stability of thelatter protease in solution allows the handling of larger quantities.Thus, more efficient and economic blending processes are possible on thebasis if the present invention.

Prior to step (d) the total protein content in the homogeneous solutionmade in step (c) is preferably in the range of about 1 mg/ml to about150 mg/ml, more preferred in the range of about 5 mg/ml to about 100mg/ml. The concentration of CaCl₂ in said homogeneous solution made instep (c) is preferably in the range of about 1 mM to about 10 mM, morepreferred in the range of about 3 mM to about 5 mM. The concentration ofthe neutral salt in said homogeneous solution made in step (c) ispreferably in the range of about 50 mM to about 500 mM, more preferredin the range of about 50 mM to about 250 mM, even more preferred in therange of about 50 mM to about 200 mM or less than 200 mM.

As a result of the freeze-drying step (d) of the inventive process asolid composition (lyophilizate) is obtained, wherein the composition isfree of acetate salt and wherein the composition comprises one or moreproteolytic enzymes with collagenase activity and a neutral protease.Typically, the lyophilizate consists of crystalline matter consisting oflamellae which are aligned in parallel (see also FIG. 1). Apparently,the structure of the lyophilizate provides a very large surface. As aresult, upon contacting the lyophilizate with water, the solid matterdissolves very rapidly, usually within 3 min or less.

Rapid formation of a protease solution is an important factor when theprotease mixture is to be used in the dissociation of tissue into singlecells. The shorter the time to dissolve the proteases, the lessproteolytic activity is lost due to auto-proteolysis occurring prior tothe application of the proteases to the tissue. Thus, the inventionprovides an important basis for improved methods of tissue dissociation.

Yet, in more detail, the present invention comprises the following itemswhich are preferred embodiments:

-   1. A solid composition comprising one or more proteolytic enzymes    with collagenase activity (C), and a neutral protease (NP),    characterized in that the composition is free of acetate salt.-   2. The composition according to item 1, characterized in that the    composition comprises sodium chloride, calcium chloride, and a    buffer salt, preferably an organic buffer salt.-   3. The composition according to any of the items 1 and 2,    characterized in that the buffer salt is capable of buffering in the    range of about pH 6 to about pH 8.5.-   4. The composition according to any of the items 1 to 3,    characterized in that the buffer salt is a compound selected from    the group consisting of BES    (N,N-Bis(2-hydroxyethyl)-2-aminoethanesulfonic acid), Tris    (2-Amino-2-(hydroxymethyl)propane-1,3-diol), BisTris    (Bis(2-hydroxyethyl)amino-tris(hydroxymethyl)methane), BisTris    propane (1,3-bis(tris(hydroxymethyl)methylamino)propane), HEPES    (N-(2-hydroxyethyl)-piperazine-N′-2-ethanesulfonic acid), MES    (2-(N-morpholino)ethanesulfonic acid), MOPS    (3-(N-morpholino)propanesulfonic acid), MOPSO    (3-morpholino-2-hydroxypropanesulfonic acid), PIPES    (Piperazine-1,4-bis(2-ethanesulfonic acid)), TAPS    (N-Tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid), TES    (N-Tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid), TEA    (Triethanolamine), and Tricine    (N-(2-Hydroxy-1,1-bis(hydroxymethyl)ethyl)glycine.-   5. The composition according to item 4, characterized in that the    buffer salt is HEPES.-   6. The composition according to any of the items 1 to 5,    characterized in that the composition is a lyophilizate, i.e.,    obtained by a freeze-drying process.-   7. The composition according to any of the items 1 to 6,    characterized in that the proteolytic enzymes with collagenase    activity in the composition are collagenase I (C1) and/or    collagenase II (CII) from Clostridium histolyticum.-   8. The composition according to any of the items 1 to 7,    characterized in that the NP in the composition is thermolysin from    Bacillus thermoproteolyticus.-   9. The composition according to any of the items 1 to 8,    characterized in that the weight-by-weight ratio of the neutral    protease versus all proteases present in the composition    (NP/(NP+C)[w/w]) is in the range of about 1 to about 25.-   10. The composition according to item 9, characterized in that    NP/(NP+C) [w/w] is in the range of about 2 to about 22.-   11. The composition according to item 9, characterized in that    NP/(NP+C) [w/w] is about 2.-   12. The composition according to item 9, characterized in that    NP/(NP+C) [w/w] is about 3.-   13. The composition according to item 9, characterized in that    NP/(NP+C) [w/w] is about 22.-   14. The composition according to any of the items 1 to 13,    characterized in that the weight-by-weight ratio of all proteases    present in the composition and sodium chloride ((NP+C)/NaCl[w/w]) is    in the range of about 0.1 to about 5.-   15. The composition according to item 14, characterized in that the    (NP+C)/NaCl[w/w] is in the range of about 0.15 to about 3.-   16. The composition according to item 14, characterized in that the    (NP+C)/NaCl[w/w] is in the range of about 0.18 to about 2.-   17. The composition according to item 14, characterized in that the    (NP+C)/NaCl[w/w] is about 0.18.-   18. The composition according to item 14, characterized in that the    (NP+C)/NaCl[w/w] is about 1.3.-   19. The composition according to item 14, characterized in that the    (NP+C)/NaCl[w/w] is about 2.-   20. The composition according to any of the items 1 to 19,    characterized in that the weight-by-weight ratio of all proteases    present in the composition and calcium chloride hexahydrate    ((NP+C)/CaCl₂[w/w]) is in the range of about 10 to about 500.-   21. The composition according to item 20, characterized in that    (NP+C)/CaCl₂[w/w] is in the range of about 15 to about 470.-   22. The composition according to item 20, characterized in that    (NP+C)/CaCl₂[w/w] is about 17.5.-   23. The composition according to item 20, characterized in that    (NP+C)/CaCl₂[w/w] is about 240.-   24. The composition according to item 20, characterized in that    (NP+C)/CaCl₂[w/w] is about 470.-   25. The composition according to any of the items 1 to 24,    characterized in that the weight-by-weight ratio of all proteases    present in the composition and the buffer salt ((NP+C)/buffer salt    [w/w]) is in the range of about 0.05 to about 2.-   26. The composition according to item 25, characterized in that    (NP+C)/buffer [w/w] is in the range of about 0.1 to about 1.-   27. The composition according to item 25, characterized in that    (NP+C)/buffer [w/w] is about 0.1.-   28. The composition according to item 25, characterized in that    (NP+C)/buffer [w/w] is about 0.5.-   29. The composition according to item 25, characterized in that    (NP+C)/buffer [w/w] is about 1.-   30. The composition according to any of the items 25 to 29,    characterized in that the buffer salt is selected from the group    consisting of BES (N,N-Bis(2-hydroxyethyl)-2-aminoethanesulfonic    acid), Tris (2-Amino-2-(hydroxymethyl)propane-1,3-diol), BisTris    (Bis(2-hydroxyethyl)amino-tris(hydroxymethyl)methane), BisTris    propane (1,3-bis(tris(hydroxymethyl)methylamino)propane), HEPES    (N-(2-hydroxyethyl)-piperazine-N′-2-ethanesulfonic acid), MES    (2-(N-morpholino)ethanesulfonic acid), MOPS    (3-(N-morpholino)propanesulfonic acid), MOPSO    (3-morpholino-2-hydroxypropanesulfonic acid), PIPES    (Piperazine-1,4-bis(2-ethanesulfonic acid)), TAPS    (N-Tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid), TES    (N-Tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid), TEA    (Triethanolamine), and Tricine    (N-(2-Hydroxy-1,1-bis(hydroxymethyl)ethyl)glycine.-   31. An aqueous solution comprising water and, in dissolved form, a    composition according to any of the items 1 to 30.-   32. The aqueous solution according to item 31, characterized in that    the pH of the solution is in the range of pH 7 to pH 8, and more    preferred pH 7.5.-   33. The aqueous solution according to any of the items 31 and 32,    characterized in that the concentration of proteases in the solution    is in the range of 0.1 mg/ml to 100 mg/ml.-   34. The aqueous solution according to item 33, characterized in that    the concentration of proteases in the solution is in the range of    about 1 mg/ml to about 75 mg/ml.-   35. The aqueous solution according to item 34, characterized in that    the concentration of proteases in the solution is in the range of    about 5 mg/ml to about 50 mg/ml.-   36. Use of an aqueous solution according to any of the items 31 to    35 for treating a biological tissue.-   37. A kit comprising package material and one or more containers    containing a solid composition according to any of the items 1 to    30.-   38. The kit according to item 37, characterized in that the one or    more containers are sealed, thereby protecting the composition in    the containers from moisture.-   39. A method to prepare a solution with proteases, comprising the    step of contacting a composition according to any of the items 1 to    30 with water.-   40. The method according to item 39, characterized in that measured    amounts of the composition and water are mixed, in order to yield a    concentration of proteases in solution, said concentration being in    the range of about 5 mg/ml to about 50 mg/ml.-   41. The method according to any of the items 39 and 40,    characterized in that a homogeneous solution is obtained within a    period in the range of less than about 1 min to 3 min, or within the    period of less than 3 min, counted from the moment the composition    is contacted with water.-   42. The method according to any of the items 40 and 41,    characterized in that the concentration of proteases is in the range    of about 5 mg/ml to about 30 mg/ml, and a homogeneous solution is    obtained within a period of less than about 1 min, counted from the    moment the composition is contacted with water.-   43. The method according to any of the items 40 and 41,    characterized in that the concentration of proteases is in the range    of about 15 mg/ml to about 50 mg/ml, and a homogeneous solution is    obtained within a period of about 3 min or shorter than 3 min,    counted from the moment the composition is contacted with water.

The figures and following examples are provided to aid the understandingof the present invention, the true scope of which is set forth in theappended claims. It is understood that modifications can be made in theprocedures set forth without departing from the spirit of the invention.

Example 1: Materials, General Conditions, and Procedures Applied

If not stated otherwise, all aqueous solutions were kept and used attemperatures between 2° C. and 8° C.

Clostridium histolyticum collagenases I and II were provided separately,in purified form. Before any of the blending procedures describedherein, collagenase I and collagenase II were each purified tohomogeneity. Each collagenase was provided in dissolved form, at aconcentration of 55 mg/ml in a buffer containing 1 mM CaCl₂, 5 mM HEPES,pH 7.5.

The major parts of a freeze drying (lyophilization) procedure includefreezing, primary drying (sublimation), and secondary drying(desorption). One objective of freezing is to produce a frozen matrixwith sufficient crystal structure to allow the sublimating material toescape. Some products form a glassy material and annealing may berequired during the freezing process. Annealing, first lowering thetemperature then raising the temperature and then lowering it again,locks the constituents in place and then allows the crystals to grow.Freezing can range from 1 hour to 24 hours, depending on theapplication. Primary drying (sublimation) drives the unbound moistureout of the product. Sublimation occurs under vacuum with the producttemperature below its critical temperature. At the end of the primarydrying cycle, the product will usually have 3% to 5% moisture content.Secondary drying (desorption) drives the water which is bound byelectrostatic and/or ionic forces from the material. This is done byheating the product. Secondary drying can result in moisture levels of0.5% or less.

Lyophilizates of protease blends according to the invention wereprepared using a lyophilizator containing a chamber with deep-frozenplates and a separate chamber consisting of a condenser all manufacturedby HSK (Germany), and according to the instructions by the manufacturer.An exemplary lyophilization process comprised the following steps andconditions:

time No. Step (hh:mm) temp. pressure comment 1. loading of 00:03  2° C.ambient enzyme pressure solution 2. Freezing 00:30 −50° C. ambienttemperature pressure may fluctuate by ±4° C. 3. Freezing 04:00 −50° C.ambient pressure 4. Evacuating 00:20 −50° C. 0.01 mbar 5. primary drying00:40 −50° C. 0.01 mbar

In the present freeze drying processes, three different regimens for theinitial secondary drying were used. One step selected from either 6a,6b, or 6c was performed.

time No. Step (hh:mm) temp. pressure comment 6a. initial 14:00 −8° C.0.01 mbar secondary drying 6b. initial 20:00 −8° C. 0.01 mbar secondarydrying 6c. initial 10:00 22° C. 0.01 mbar temperature secondary mayfluctuate drying by ±3° C.

Following the initial secondary drying step the following regimen wasapplied. The partial aeration steps 8. and 10 were optional.

time No. Step (hh:mm) temp. pressure comment  7. secondary drying 06:0022° C. 0.01 mbar  8. partial aeration (test) 00:02 22° C. 0.17 mbar  9.secondary drying 03:30 22° C. 0.01 mbar 10. partial aeration (test)00:02 22° C. 0.05 mbar 11. aeration with N₂ 00:01 22° C.  700 mbar 12.incubation 00:05 22° C.  700 mbar 13. aeration with N₂ 00:01 22° C.ambient pressure 14. unloading 00:03  4° C. ambient pressure 15. storage 4° C. ambient pressure

Example 2: Preparation of Crystallized Thermolysin and Solubilization ofCrystallized Thermolysin

Thermolysin (EC 3.4.24.27) was obtained as a freeze-dried, amorphouspowder from Daiwa Kasei K. K. (Japan) containing at least about 60%[w/w] of enzyme protein, about 20% [w/w] of anhydrous Calcium acetate(Ca-acetate or CaAc), and about 10% [w/w] of anhydrous Sodium acetate(Na-acetate or NaAc). In case thermolysin in the presence of acetate wasused, twice crystallized thermolysin was used. For a crystallizationstep, thermolysin lyophilizate was suspended at a concentration in therange of between about 1% [w/v] to about 3% [w/v] in an ice-cold aqueoussolution of Calcium acetate at a concentration of 0.01 M. thermolysinwas dissolved by adding 0.2 N NaOH drop-wise and under agitation, untilthe pH of the solution was between pH 11.0 and pH 11.4. After removal ofany undissolved residue (if found to be present), the solution wasneutralized to pH 6.0 with 0.2 N acetic acid. Crystallization usuallywas complete after about 2 days. During the whole process ice-coldtemperatures were maintained. The crystals were recovered andfreeze-dried under standard conditions.

An exemplary lyophilizate of crystallized thermolysin had a proteincontent of about 66.1% [w/w] and was used in blending experiments.

Before blending, the crystallized thermolysin lyophilizate was suspendedin aqueous HEPES buffer (1 mM CaCl₂, 5 mM HEPES, pH 7.5). In order todissolve the protein, about 7.2 mM NaOH were added (as 0.1 N NaOH) toraise the pH to a value of about pH 11. Subsequently, the pH was loweredto pH 7.5 by admixing 0.5 M HEPES solution which was not titrated withhydroxide and therefore acidic. The final volume of the solution wasadjusted with HEPES buffer (1 mM CaCl₂, 5 mM HEPES, pH 7.5). The finalprotein concentration in the solution was between 13.1 mg/ml and 13.2mg/ml. Notably, a clear solution was obtained which, however, was notstable. It was observed that the resulting solution became turbid afterabout 30 min due to beginning precipitation of thermolysin. Only smallamounts of thermolysin solution could be prepared using the abovemethod. As a further disadvantage, the small volume of thermolysinsolution had to be used instantly in the blending process in whichenzyme in homogeneous solution is required. Because the blending processtakes a certain amount of time it has to be assured that the thermolysinenzyme solution is homogeneous during the whole process.

Example 3: Preparation of a Stabilized Solution Containing Thermolysin

In view of the shortcomings described in Example 2, a more favorablemethod for providing thermolysin in homogeneous solution was developed.A further preparation containing crude thermolysin (EC 3.4.24.27) isavailable from Daiwa Kasei K. K. (Japan) under the trade name THERMOASE.The THERMOASE quality of thermolysin used here was a lyophilisate. Theprotein content of “crude thermolysin” in the lyophilizate was about 33%[w/w]. About 65% [w/w] of the lyophilisate was NaCl. The remainingamount of about 2% [w/w] was Na₂SO₄. “Crude thermolysin” in the presentcontext is a protein mixture consisting of

-   -   (i) about 70% substantially undegraded (intact) thermolysin,    -   (ii) about 24% of thermolysin degradation products which retain        proteolytic activity (to different degrees), and    -   (iii) about 6% of proteolytically inactive fragments and further        impurities.

A volume of 6.5 l of an aqueous buffer containing 5 mM CaCl₂, 20 mMHEPES, pH 7.5 was prepared. An amount of 200 g dry THERMOASElyophilisate was dissolved in the aqueous buffer and a clear solutionwas obtained. Subsequently, 935 g solid NaCl was added and dissolved inthe solution. The volume of the solution was adjusted to 8 l by adding afurther volume of the aqueous buffer containing 5 mM CaCl₂, 20 mM HEPES,pH 7.5, and mixing by stirring. A homogeneous solution was obtained.Taking into account that about 65% [w/w] of the lyophilisate consists ofNaCl, the final NaCl concentration in the solution was about 2.3 M. Thefinal concentration of crude thermolysin (about 33% [w/w] of thelyophilisate) in the solution was about 8.25 mg/ml corresponding to aconcentration of substantially undegraded thermolysin of about 5.8 mg/mlin the solution.

The solution of thermolysin produced as described above was stable forat least 20 hours and up to 48 hours. That is to say, no precipitate wasformed in the solution during this time. Under other conditions,particularly when the amount of NaCl was dissolved in the buffer priorto adding THERMOASE lyophilizate, beginning precipitation of thermolysincould be observed after about an hour. Therefore the stabilized solutioncontaining thermolysin allowed extensive further processing, includingremoval of small proteolytic fragments by way of diafiltration, andsubsequent blending using larger volumes of thermolysin solution.

Diafiltration was performed using a filter with an exclusion limit ofabout 10 kDa and against an aqueous buffer containing 5 mM CaCl₂, 170 mMNaCl, 20 mM HEPES, pH 7.5. The final protein concentration afterdiafiltration was between about 2.25 mg/ml and about 2.75 mg/ml in thediafiltration buffer. The conductivity of the diafiltrated thermolysinsolution was 21.2±1 mS/cm.

Diafiltrated thermolysin was either used directly in blending processes,or the solution was aliquoted and aliquots were frozen and stored at−20° C. Frozen aliquots were thawed before use and remained stableafterwards for 6 hours or more.

Example 4: Preparation of a Lyophilized Thermolysin-Containing Blend ofProteases (Blend 1) with a Low Amount of Thermolysin

The blend contained collagenase I, collagenase II and thermolysin.Collagenase solutions according to Example 1 and thermolysin solutionaccording to Example 2 were mixed according to Table 1. The resultingmixture had the final volume as indicated in the table and waslyophilized immediately after addition of the last component. Thelyophilizate which was obtained consisted of white crystals which in thefreeze-drying process formed unordered clusters. The morphology of thelyophilizate corresponded to the lyophilizate depicted in FIG. 1A.

TABLE 1 concentration vol. of stock concentration amount in stocksolution in in final substance (absolute) solution mixture mixturecollagenase I 26,565 mg 55 mg/ml 483 ml 29.3 mg/ml collagenase II 17,435mg 55 mg/ml 317 ml 19.2 mg/ml thermolysin 1,265 mg ^($) 13.2 mg/ml 96.6ml 1.4 mg/ml Protein conc. total 45,265 mg 49.9 mg/ml NaAc total 2.6 mMCaAc total 3 mM CaCl₂ total 0.8 mM NaOH 0.1N 9 ml 1 mM HEPES total 5.2mM HEPES^(‡) 0.5M 1.5 ml HEPES^(§) buffer — Volume total 907.1 ml pH 7.5^(‡)HEPES solution, not alkali-titrated; for neutralization ^(§)HEPESbuffer (1 mM CaCl₂, 5 mM HEPES, pH 7.5) for volume adjustment, ifnecessary ^($) corresponding to 1,914 mg of lyophilized crystals (i.e.,including solid Calcium acetate, see Example 2)

Example 5: Preparation of a Lyophilized Thermolysin-Containing Blend ofProteases (Blend 2) with a Medium Amount of Thermolysin

The blend contained collagenase I, collagenase II and thermolysin.Collagenase solutions according to Example 1 and thermolysin solutionaccording to Example 2 were mixed according to Table 2. The resultingmixture had the final volume as indicated in the table and waslyophilized immediately after addition of the last component. Thelyophilizate which was obtained consisted of white crystals which in thefreeze-drying process formed unordered clusters. The morphology of thelyophilizate corresponded to the lyophilizate depicted in FIG. 1A.

TABLE 2 concentration volume of stock concentration amount in stocksolution in in final substance (absolute) solution mixture mixturecollagenase I 8,580 mg 55 mg/ml 156 ml 8.2 mg/ml collagenase II 5,610 mg55 mg/ml 102 ml 5.4 mg/ml thermolysin 5,585 mg ^($) 13.1 mg/ml 422 ml5.3 mg/ml Protein total 19,775 mg 18.9 mg/ml NaAc total 9.9 mM CaActotal 11.6 mM CaCl₂ total 0.5 mM NaOH 0.1N 75 ml 7.2 mM HEPES total 5.9mM HEPES^(‡) 0.5M 7 ml HEPES^(§) buffer solution 283 ml Volume total1,045 ml pH 7.5 ^(‡)HEPES solution, not alkali-titrated; forneutralization ^(§)HEPES buffer (1 mM CaCl₂, 5 mM HEPES, pH 7.5) forvolume adjustment, if necessary ^($) corresponding to 8,449 mg oflyophilized crystals (i.e., including solid Calcium acetate, see Example2)

Example 6: Preparation of a Lyophilized Thermolysin-Containing Blend ofProteases (Blend 3) with a High Amount of Thermolysin

The blend contained collagenase I, collagenase II and thermolysin.Collagenase solutions according to Example 1 and thermolysin solutionaccording to Example 2 were mixed according to Table 3. The resultingmixture had the final volume as indicated in the table and waslyophilized immediately after addition of the last component. Thelyophilizate which was obtained consisted of white crystals which in thefreeze-drying process formed unordered clusters. The morphology of thelyophilizate corresponded to the lyophilizate depicted in FIG. 1A.

TABLE 3 concentration volume of stock concentration amount in stocksolution in in final substance (absolute) solution mixture mixturecollagenase I 2,140 mg 55 mg/ml 38.9 ml 5.6 mg/ml collagenase II 1,422mg 55 mg/ml 25.85 ml 3.7 mg/ml thermolysin 2,772 mg $ 13.2 mg/ml 211 ml7.2 mg/ml Protein total 6,334 mg 16.5 mg/ml NaAc total 13.4 mM CaActotal 15.7 mM CaCl2 total 0.4 mM NaOH 0.1N 19 ml 5 mM HEPES total 4.5 mMHEPES‡ 0.5M 2 ml HEPES§ buffer solution 85.75 ml Volume total 382.5 mlpH 7.5 ‡HEPES solution, not alkali-titrated; for neutralization §HEPESbuffer (1 mM CaCl₂, 5 mM HEPES, pH 7.5) for volume adjustment, ifnecessary $ corresponding to 4,194 mg of lyophilized crystals (i.e.,including solid Calcium acetate, see Example 2)

Example 7: Preparation of an Acetate-Free Thermolysin-Containing Blendof Proteases (Blend 4)

The blend contained collagenase I, collagenase II and thermolysin.Collagenase solutions according to Example 1 and diafiltrated stabilizedthermolysin solution according to Example 3 were mixed according toTable 4. The resulting mixture had the final volume as indicated in thetable and was lyophilized immediately after addition of the lastcomponent. The lyophilizate which was obtained consisted of whitecrystals which in the freeze-drying process formed lamellae orblade-like structures of which most were aligned in parallel. Themorphology of the lyophilizate corresponded to the lyophilizate depictedin FIG. 1B.

TABLE 4 concentration volume of stock concentration amount in stocksolution in in final substance (absolute) solution mixture mixturecollagenase I 410 mg 55 mg/ml 7.45 ml 16 mg/ml collagenase II 275 mg 55mg/ml 5 ml 10.7 mg/ml thermolysin^(‡) 33 mg 2.5 mg/ml 13.2 ml 1.3 mg/mlProtein total 718 mg 28 mg/ml CaCl₂ total 3.1 mM NaCl 87 mM HEPES total12.8 mM Volume total 25.65 ml pH 7.5 ^(‡)the total amount of proteinpresent in the stabilized solution after diafiltration, see Example 3

Example 8: Preparation of an Acetate-Free Thermolysin-Containing Blendof Proteases (Blend 5)

The blend contained collagenase I, collagenase II and thermolysin.Collagenase solutions according to Example 1 and diafiltrated stabilizedthermolysin solution according to Example 3 were mixed according toTable 5. The resulting mixture had the final volume as indicated in thetable and was lyophilized immediately after addition of the lastcomponent. The lyophilizate which was obtained consisted of whitecrystals which in the freeze-drying process formed lamellae orblade-like structures of which most were aligned in parallel. Themorphology of the lyophilizate corresponded to the lyophilizate depictedin FIG. 1B.

TABLE 5 concentration volume of stock concentration amount in stocksolution in in final substance (absolute) solution mixture mixturecollagenase I 660 mg 55 mg/ml 12 ml 2.85 mg/ml collagenase II 440 mg 55mg/ml 8 ml 1.9 mg/ml thermolysin^(‡) 530 mg 2.5 mg/ml 212 ml 2.3 mg/mlProtein total 1,630 mg 7.05 mg/ml CaCl₂ total 4.7 mM NaCl 155 mM HEPEStotal 18.7 mM Volume total 232 ml pH 7.5 ^(‡)the total amount of proteinpresent in the stabilized solution after diafiltration, see Example 3

Example 9: Preparation of an Acetate-Free Thermolysin-Containing Blendof Proteases (Blend 6)

The blend contained collagenase I, collagenase II and thermolysin.Collagenase solutions according to Example 1 and diafiltrated stabilizedthermolysin solution according to Example 3 were mixed according toTable 6. The resulting mixture had the final volume as indicated in thetable and was lyophilized immediately after addition of the lastcomponent. The lyophilizate which was obtained consisted of whitecrystals which in the freeze-drying process formed lamellae orblade-like structures of which most were aligned in parallel. Themorphology of the lyophilizate corresponded to the lyophilizate depictedin FIG. 1B.

TABLE 6 concentration volume of stock concentration amount in stocksolution in in final substance (absolute) solution mixture mixturecollagenase I 660 mg 55 mg/ml 12 ml 1.5 mg/ml collagenase II 440 mg 55mg/ml 8 ml 1 mg/ml thermolysin^(‡) 1,060 mg 2.5 mg/ml 424 ml 2.4 mg/mlProtein total 2,160 mg 4.9 mg/ml CaCl₂ total 4.8 mM NaCl 162 mM HEPEStotal 19.3 mM Volume total 444 ml pH 7.5 ^(‡)the total amount of proteinpresent in the stabilized solution after diafiltration, see Example 3

Example 10: Solubilization of Lyophilizates

Lyophilized blends in sealed bottles were dissolved in different amountsof purified water, in order to yield solutions with different proteinconcentrations. The bottles were put on a roller device and agitated at32 revolutions per minute at 20° C. The time needed to dissolve thelyophilizates was recorded. Recordings were stopped after 75 min, evenif solubilization was not complete at this point. Table 7 indicates thetime intervals needed for dissolving the lyophilizates according to eachof Example 4 to 9. Completeness of solubilization (i.e., the factwhether or not a homogeneous solution was obtained) was assessed byvisual inspection or by turbidity measurements.

TABLE 7 protein concentration in solution (after time needed forsolubilization), solubilization, Blend # in [mg/ml] in [min] 1 49.9 3 125 3 2 18.9 75 2 7 75 3 16.5 75 3 5.5 75 4 47 3 4 28 <1 5 21 3 5 7 <1 617 3 6 5 <1

Example 11: Solubilization of Lyophilizates

Under the same conditions as described in Example 10, lyophilized blendsin sealed bottles were dissolved in different amounts of purified water,in order to yield solutions with different protein concentrations. Thetime needed to dissolve the lyophilizates was recorded. Recordings werestopped after 75 min, even if solubilization was not complete at thispoint. Completeness of solubilization was firstly assessed by visualinspection. Secondly. the turbidity of each obtained solution wasmeasured by determining its optical density (OD) at a wavelength 600 nmusing standard quartz cuvettes and a photometer. Table 8 indicates thetime intervals needed for dissolving the lyophilizates as well as theresults of the assessments of turbidity.

TABLE 8 protein concentration in turbidity as turbidity as solution(after time needed for determined determined solubilization),solubilization, by OD at by visual Blend # in [mg/ml] in [min] 600 nminspection 1 49.9 3 0.013 clear 1 25 3 0.014 clear 2 18.9 75 2.159^(¥)opaque, precipitate 2 7 75 0.979 opaque, precipitate 3 16.5 75 2.127^(¥)opaque, precipitate 3 5.5 75 1.665 opaque, precipitate 4 47 3 0.033clear 4 28 <1 0.026 clear 5 21 3 0.078 clear 5 7 <1 0.037 clear 6 17 30.088 clear 6 5 <1 0.078 clear ^(¥)measurement out of range ofproportionality

What is claimed is:
 1. A method for producing a solid compositioncomprising the steps of: preparing a homogeneous solution of anacetate-free preparation of a neutral protease (NP) in an aqueousacetate-free, low-salt solution, wherein the low-salt solution has anaggregate concentration of salt(s) in the range of about 1 mM to about250 mM; adding a neutral salt to the homogeneous solution and dissolvingthe neutral salt, thereby making a stabilized solution, wherein thestabilized solution additionally comprises a buffer salt buffering in arange of about pH 6 to about pH 8.5, and wherein the stabilized solutionfurther comprises calcium chloride; mixing the stabilized solution withan acetate-free preparation of one or more proteolytic enzymes withcollagenase activity (C) and making a homogeneous solution; andfreeze-drying the homogeneous solution, thereby obtaining the solidcomposition.
 2. The method according to claim 1, wherein the neutralprotease is thermolysin from Bacillus thermoproteolyticus.
 3. The methodaccording to claim 1, wherein a weight/weight ratio of the neutralprotease versus all proteases present in the composition (NP/(NP+C)) isin a range of about 1 to about
 25. 4. The method according to claim 1,wherein the neutral salt is sodium chloride and a weight/weight ratio ofall proteases present in the composition versus sodium chloride((NP+C)/NaCl) is in a range of about 0.1 to about
 5. 5. The methodaccording to claim 1, wherein a weight/weight ratio of all proteasespresent in the composition versus calcium chloride ((NP+C)/CaCl₂) is ina range of about 10 to about
 500. 6. The method according to claim 1,wherein a weight/weight ratio of all proteases present in thecomposition versus the buffer salt ((NP+C)/buffer) is in a range ofabout 0.05 to about
 2. 7. The method of claim 1, wherein the solidcomposition further comprises sodium chloride, calcium chloride, and anorganic buffer salt.
 8. The method of claim 1 further comprising thestep of contacting the solid composition obtained in said step offreeze-drying with water.
 9. The method of claim 8, wherein upon saidfurther step of contacting, the proteases in solution have aconcentration in a range of about 5 mg/ml to about 50 mg/ml.
 10. Themethod of claim 9, wherein upon said further step of contacting, ahomogeneous solution is obtained within a period of about 3 minutes orless than 3 minutes.